1,808 research outputs found
Measurements of Total Hemispherical Emissivity of Several Stably Oxidized Nickel-Titanium Carbide Cemented Hard Metals from 600 F to 1,600 F
The total hemispherical emissivity of several nickel-titanium carbide cemented hard metals have been measured over a temperature range from 600 F to l,600 F. A variety of cemented hard metals were obtained from the Kennametal Corporation. A brief discussion of the apparatus employed and the procedures used for this investigation is included. The results of the tests of specimens in the as-received and polished states indicate a nearly constant emissivity for each material tested over the temperature range considered and only slight differences in emissivity values for the different materials. Values obtained on the stably oxidized specimens range from 0.90 to 0.94 at 6000 F and o.88 to 0.92 at 1,600 F for the as-received specimens and from 0.82 to 0.89 at 600 F and 0.85 to 0.87 at 1,600 F for the polished specimens. The surface analysis of the oxidized materials as obtained by X-ray diffraction methods and metallographic techniques are presented as an aid to reproducing the surface on which these measurements were made
Allied Chemical, the Kepone Incident, and the Settlements: Twenty Years Later
Twenty years ago this July the happenings at a small chemical plant in Hopewell, Virginia ushered in what has since become an incident of national impact and importance. Through the prosecution of criminal cases, the filing of civil personal injury suits and the closing of the James River to fishing, the release of the chemical from the Kepone manufacturing process gained national attention
Selective functionalization of carbon nanotube tips allowing fabrication of new classes of nanoscale sensing and manipulation tools
Embodiments in accordance with the present invention relate to techniques for the growth and attachment of single wall carbon nanotubes (SWNT), facilitating their use as robust and well-characterized tools for AFM imaging and other applications. In accordance with one embodiment, SWNTs attached to an AFM tip can function as a structural scaffold for nanoscale device fabrication on a scanning probe. Such a probe can trigger, with nanometer precision, specific biochemical reactions or conformational changes in biological systems. The consequences of such triggering can be observed in real time by single-molecule fluorescence, electrical, and/or AFM sensing. Specific embodiments in accordance with the present invention utilize sensing and manipulation of individual molecules with carbon nanotubes, coupled with single-molecule fluorescence imaging, to allow observation of spectroscopic signals in response to mechanically induced molecular changes. Biological macromolecules such as proteins or DNA can be attached to nanotubes to create highly specific single-molecule probes for investigations of intermolecular dynamics, for assembling hybrid biological and nanoscale materials, or for developing molecular electronics. In one example, electrical wiring of single redox enzymes to carbon nanotube scanning probes allows observation and electrochemical control over single enzymatic reactions by monitoring fluorescence from a redox-active cofactor or the formation of fluorescent products. Enzymes ''nanowired'' to the tips of carbon nanotubes in accordance with embodiments of the present invention, may enable extremely sensitive probing of biological stimulus-response with high spatial resolution, including product-induced signal transduction
Mass and Angular Momentum Transfer in the Massive Algol Binary RY Persei
We present an investigation of H-alpha emission line variations observed in
the massive Algol binary, RY Per. We give new radial velocity data for the
secondary based upon our optical spectra and for the primary based upon high
dispersion UV spectra. We present revised orbital elements and an estimate of
the primary's projected rotational velocity (which indicates that the primary
is rotating 7 times faster than synchronous). We use a Doppler tomography
algorithm to reconstruct the individual primary and secondary spectra in the
region of H-alpha, and we subtract the latter from each of our observations to
obtain profiles of the primary and its disk alone. Our H-alpha observations of
RY Per show that the mass gaining primary is surrounded by a persistent but
time variable accretion disk. The profile that is observed outside-of-eclipse
has weak, double-peaked emission flanking a deep central absorption, and we
find that these properties can be reproduced by a disk model that includes the
absorption of photospheric light by the band of the disk seen in projection
against the face of the star. We developed a new method to reconstruct the disk
surface density distribution from the ensemble of H-alpha profiles observed
around the orbit, and this method accounts for the effects of disk occultation
by the stellar components, the obscuration of the primary by the disk, and flux
contributions from optically thick disk elements. The resulting surface density
distribution is elongated along the axis joining the stars, in the same way as
seen in hydrodynamical simulations of gas flows that strike the mass gainer
near trailing edge of the star. This type of gas stream configuration is
optimal for the transfer of angular momentum, and we show that rapid rotation
is found in other Algols that have passed through a similar stage.Comment: 39 pages, 12 figures, ApJ in press, 2004 June 20 issu
Survival Estimates of Western Gray Whales \u3ci\u3eEschrichtius robustus\u3c/i\u3e Incorporating Individual Heterogeneity and Temporary Emigration
Gray whales Eschrichtius robustus exist as a 2 geographically and genetically distinct populations in the eastern and western North Pacific. Subjected to intensive commercial whaling during the 19th and 20th centuries, the western population presently numbers approximately 100 individuals and is regarded as one of the most endangered baleen whale populations in the world
Survival Estimates of Western Gray Whales \u3ci\u3eEschrichtius robustus\u3c/i\u3e Incorporating Individual Heterogeneity and Temporary Emigration
Gray whales Eschrichtius robustus exist as a 2 geographically and genetically distinct populations in the eastern and western North Pacific. Subjected to intensive commercial whaling during the 19th and 20th centuries, the western population presently numbers approximately 100 individuals and is regarded as one of the most endangered baleen whale populations in the world
Tomographic Separation of Composite Spectra. VIII. The Physical Properties of the Massive Compact Binary in the Triple Star System HD 36486 (delta Orionis A)
Double-lined spectroscopic orbital elements have recently been found for the
central binary in the massive triple, delta Orionis A based on radial
velocities from cross-correlation techniques applied to IUE high dispersion
spectra and He I 6678 spectra obtained at Kitt Peak. The primary and secondary
velocity amplitudes were found to be 94.9 +/- 0.6 km/s and 186 +/- 9 km/s
respectively. Tomographic reconstructions of the primary and secondary stars'
spectra confirm the O9.5 II classification of the primary and indicate a B0.5
III type for the secondary. The widths of the UV cross-correlation functions
are used to estimate the projected rotational velocities, Vsin i = 157 +/- 6
km/s and 138 +/- 16 km/s for the primary and secondary, respectively implying
that both stars rotate faster than their orbital motion. We used the
spectroscopic results to make a constrained fit of the Hipparcos light curve of
this eclipsing binary, and the model fits limit the inclination to the range
between 67 and 77 degrees. The i = 67 degrees solution, which corresponds to a
near Roche-filling configuration, results in a primary mass of 11.2 solar
masses and a secondary mass of 5.6 solar masses, both of which are
substantially below the expected masses for stars of their luminosity. This
binary may have experienced a mass ratio reversal caused by Case A Roche lobe
overflow, or the system may have suffered extensive mass loss through a binary
interaction, perhaps during a common envelope phase, in which most of the
primary's mass was lost from the system rather than transferred to the
secondary.Comment: 27 pages, 15 figures in press, the Astrophysical Journal, February 1,
200
Volume 17. Article 1. Oceanography of Long Island Sound.
https://elischolar.library.yale.edu/bulletin_yale_bingham_oceanographic_collection/1157/thumbnail.jp
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